This invention relates to an optically anisotropic thin film and a process for producing the same. More particularly, it relates to a thin film having light absorption anisotropy which is useful as a louver of displays, an optical filter of various laser apparatus, and the like and an economical process for producing the same.
Systems having a function in attenuating, polarizing, scattering or shielding light including laser light and natural light have been used in a very broad range of applications, and there has been and will be an eager demand for these functions. These functions have been performed by the respective systems which operate through the respective mechanisms for the particular function. Accordingly, the products which perform the respective functions have been manufactured through the respective steps.
Such systems include those comprising an optical lens, a polarizing plate, etc. In recent years, photosemiconductors and liquid crystals have also been employed. For example, a film having a fine louver structure has been proposed, which is integrally sandwiched in between a pair of polycarbonate films to have a total thickness of about 1 mm and yet retains a louver effect. Devices having the above function are frequently used in the practice in combination with some mechanical mechanism.
Many of conventional devices used in the related art have a single function like the above-described film having a louver effect and do not perform a plurality of functions sufficiently. Apparatus which perform multiple functions need a large-sized optical system, an expensive semiconductor device or some special and expensive functional device. Further, these apparatus are not practical for mass production because of complicated steps involved. Besides, it has been very difficult to widen the area through which light is transmitted while securing uniformity in quality.
An object of the invention is to provide an optically anisotropic thin film showing anisotropy in light absorption characteristics which easily performs optical functions, such as attenuating, polarizing, scattering or shielding light including laser light and natural light.
Another object of the invention is to provide an economical process for producing such an optically anisotropic thin film.
The above objects are accomplished by (1) an optically anisotropic thin film comprising a dichroic dye which is cured while keeping prescribed orientation and (2) a process for producing the thin film comprising the steps of forming an orientation film of prescribed mode on a transparent or semitransparent substrate, applying a solution of a dichroic dye in a solvent to the orientation film, and fixing the orientation of the dichroic dye by evaporating the solvent from the dichroic dye solution.
The present invention provides an optically anisotropic thin film with which a function of attenuating, polarizing, scattering or shielding incident light including laser light can be performed with ease and a simple and economical process for producing the film.